1. Field of the Invention
The present invention relates to a distance measurement holder and a machine tool having an interfering object sensing function.
2. Description of the Related Art
Conventionally, to prevent mutual interferences between a main shaft, a cutting tool, a workpiece, a jig, and the like resulting from a faulty operation or faulty judgment by a worker during a debugging operation for a machining program, a method has been devised which measures the positions or shapes of the workpiece and the jig in some way, compares information about the positions or shapes to the movement paths of the main shaft and the cutting tool to determine the presence or absence of an interference and stops a machining motion when it is determined that an interference occurs, thereby preventing the interference.
A measurement method has been devised which involves no motion of elements such as a jig, a workpiece, a main shaft, a cutting tool, a measurement device, and a measurement device control unit during an operation of measuring the positions or shapes to prevent mutual interferences between such elements. Another method has been devised which limits the motion of such elements to a range in which no interference occurs. A non-contact method has also been devised which includes the line scanning of the interior of a working area with a laser beam, the use of information obtained through the image processing of an image on a table photographed with a camera, and the like (Japanese Patent Application Laid-Open No. 2009-265023).
However, the technique described above needs an extra device for controlling the emission direction of the laser beam or an extra processing unit for image data. This causes a problem in ensuring a space in which such devices are to be placed or the problem of a higher failure rate resulting from an increased number of parts.